Foamed molded product and manufacturing method thereof

ABSTRACT

A foamed molded product having joining flat surfaces to be joined to a joining object, in which the foaming ratio of an ordinary portion is higher than the foaming ratio of joining flat surface forming portions provided with the joining flat surfaces. Preferably, the foamed molded product has the joining flat surface forming portions on an end or both ends of the ordinary portion. Preferably, the foamed molded product has an arch portion whose sectional shape is substantially arcuate and the joining flat surfaces are provided on both ends of a concave side face of the arch portion. Preferably, when the foaming ratio of the joining flat surface forming portion is assumed to be A and the foaming ratio of the ordinary portion is assumed to be B, B/A=1.01-2.5.

CROSS-REFERENCES TO RELATED APPLICATIONS

The present application claims priority under 35 U.S.C. § 119 to Japanese Patent Application No. 2004-102182, filed Mar. 31, 2004, entitled “Foamed Molded Product and Manufacturing Method thereof”, Japanese Patent Application No. 2004-144087, filed May 13, 2004, entitled “Foamed Molded Product and Manufacturing Method thereof”, Japanese Patent Application No. 2004-144088, filed May 13, 2004, entitled “Foamed Molded Product and Manufacturing Method thereof”, Japanese Patent Application No. 2004-144089, filed May 13, 2004, entitled “Foamed Molded Product and Manufacturing Method thereof”, and Japanese Patent Application No. 2004-286292, filed Sep. 30, 2004, entitled “Foamed Molded Product and Manufacturing Method”. The contents of this application are incorporated herein by reference in their entirety.

BACKGROUND OF THE INVENTION

1. Field of the Invention

The present invention relates to a foamed molded product having joining flat surfaces to be joined to a joining object such as a side molding of an automobile and a manufacturing method of the same.

2. Discussion of the Background

For example, as the side molding of an automobile, a molded product in a solid state without being foamed has been widely used. That is, a conventional solid side molding 9, as shown in FIG. 45, includes, for example, an arch portion 90 having a substantially arcuate section and its concave side face is used as a rear surface. The side molding 9 has a plurality of ribs 915 on the rear side of a joining face forming portion 91 located on each of both ends of the arch portion 90 and a double-sided adhesive tape 99 or the like is bonded to end faces 911 thereof to join the side molding to an automobile body.

To enhance the joining performance of the side molding to the automobile body, it is necessary to form the rib 915 thicker or form a solid thick portion instead of the rib formation so as to increase an area for contact with the double-sided adhesive tape 99.

However, in any case, sink mark becomes likely to occur in the design surface of the arch portion 90, so that its appearance characteristic deteriorates, which is a problem to be solved.

The resin molded product such as the side molding has been demanded to be replaced with foamed molded product for reduction in weight. However, only if it is replaced with the foamed molded product, often its shape is not stabilized or no sufficient stiffness is obtained. Particularly, the structure and manufacturing method of foamed molded product optimal to a molded product having the joining face like the side molding have not been considered sufficiently. As the method for the foamed molding, various methods have been proposed since before (see patent documents 1, 2).

-   Patent document 1: JP 1996-244066 Unexamined Patent Publication     (Kokai) -   Patent document 2: JP 1998-180825 Unexamined Patent Publication     (Kokai)

SUMMARY OF THE INVENTION

The present invention has been accomplished in views of the above-described problems and an object of the present invention is to provide a foamed molded product having an excellent appearance and a structure suitable for a molded product having joining flat surfaces and a manufacturing method thereof.

According to a first aspect of the present invention, there is provided a foamed molded product having a joining flat surface to be joined to a joining object, the formed molded product comprising:

-   -   a joining flat surface forming portion provided with the joining         flat surface; and     -   an ordinary portion which is other portion than the joining flat         surface forming portion; and     -   wherein the foaming ratio of the joining flat surface forming         portion provided with the joining flat surface is higher than         the foaming ratio of an ordinary portion.

In the foamed molded product, as described above, the foaming ratio of the joining flat surface forming portion is lower than the foaming ratio of the ordinary portion and it is maintained at a lower foaming ratio and in a nearly solid state. Consequently, the joining flat surface forming portion having the joining flat surface has a high stiffness and is excellent in stability in configuration. Thus, when it is joined to the joining object, stable joining condition is obtained. Further, smoothness of the joining flat surface is improved so that adhesiveness to a bonding member such as double-sided adhesive tape is intensified, thereby its bonding performance being improved.

Because the foaming ratio of the ordinary portion is kept high, deterioration in appearance such as sink mark at the time of manufacturing can be prevented. The reason can be considered to be that because the foaming ratio of the ordinary portion is kept high, foaming pressure applies to not only the ordinary portion but also the joining flat surface forming portion and the boundary portion between the joining flat surface forming portion and the ordinary portion, thereby preventing sink mark and improving entire appearance characteristic.

By replacing a conventional solid product with the foamed molded product of the present invention, the joining performance with the joining object can be intensified and cost can be reduced due to reduction in weight and reduced material for use.

According to a second aspect of the present invention, there is provided a manufacturing method of foamed molded product having a joining flat surface to be joined to a joining object in which the foaming ratio of an ordinary portion is higher than the foaming ratio of a joining flat surface forming portion provided with the joining flat surface, the manufacturing method comprising:

-   -   using a mold comprising at least a fixed part and a moving part         advancing/retracting with respect to the fixed part and         containing a cavity for forming the foamed molded product, the         moving part being disposed adjacent to a joining surface forming         cavity face for forming the joining flat surface in the cavity         such that the moving part opposes the ordinary portion;     -   injecting synthetic resin material containing foaming agent or         synthetic resin material containing foaming gas into the cavity;         and     -   retracting the moving part to increase the volume of the         ordinary portion in order to urge the foaming.

According to the manufacturing method of the present invention, a mold having the fixed part and moving part is used and synthetic resin material containing foaming agent or foaming gas is injected into the cavity. At this time, the moving part opposing the ordinary portion is kept in advancing condition so as to minimize the volume of the cavity.

Next, after the injection of the synthetic resin material is completed, the moving part is retracted to increase the volume of the ordinary portion in the cavity. Accompanied by this, the synthetic resin material containing foaming agent or foaming gas is expanded convergently in the ordinary portion with pressure produced when the foaming agent or foaming gas expands. Further, material located in the joining flat surface forming portion is expanded more or less to release pressure toward the ordinary portion. By these expansion pressures, generation of sink mark at the time of molding can be suppressed so that an obtained appearance characteristic can be improved.

In the obtained foamed molded product, the joining flat surface forming portions having the joining flat surfaces are formed in a low foaming condition without changing the volume at the time of molding. Thus, a sufficient smoothness of the joining flat surface can be obtained so that the bonding performance to the joining object can be improved.

According to a third aspect of the present invention, there is provided a foamed molded product having a joining flat surface to be joined to a joining object, the formed molded product comprising:

-   -   a joining flat surface forming portion provided with the joining         flat surface; and     -   an ordinary portion which is other portion than the joining flat         surface forming portion; and     -   wherein the foaming ratio of the joining flat surface forming         portion provided with the joining flat surface and the foaming         ratio of the ordinary portion are substantially equal.

In the foamed molded product of the present invention, as described above, the foaming ratio of the ordinary portion and the foaming ratio of the joining flat surface forming portion are substantially equal. Thus, when foaming is urged at the time of manufacturing, entirely uniform foaming pressure can be obtained. Therefore, deterioration in appearance such as sink mark can be prevented, so that a foamed molded product having a very excellent appearance characteristic can be obtained.

Because the joining flat surface forming portion is formed by foamed molding, the area of the joining flat surface can be increased with respect to a case of the conventional rib and joining performance using double-sided adhesive tape or the like can be improved.

By replacing a conventional solid product with the foamed molded product of the present invention, the joining performance to the joining object can be intensified and cost can be reduced due to reduction in weight and reduced material for use.

According to a fourth aspect of the present invention, there is provided a manufacturing method of foamed molded product having a joining flat surface to be joined to a joining object in which the foaming ratio of a joining flat surface forming portion provided with the joining flat surface and the foaming ratio of an ordinary portion are substantially equal, the manufacturing method comprising:

-   -   using a mold having a fixed part and a moving part         advancing/retracting with respect to the fixed part and         containing a cavity for forming the foamed molded product, the         moving part being disposed such that it is sandwiched by the         joining surface forming cavity faces for forming the joining         flat surfaces in the cavity, the moving part opposing the         ordinary portion, wherein between the moving part and a mold         portion adjacent thereto, a heat insulating structure for         reducing heat transmission between the both is provided,     -   keeping the joining surface forming cavity face at a temperature         higher than that of the moving part while keeping the moving         part at a temperature lower than that of the joining surface         forming cavity face;     -   injecting synthetic resin material containing foaming agent or         synthetic resin material containing foaming gas into the cavity,         retracting the moving part to increase the volume of the         ordinary portion in order to urge the foaming.

According to the manufacturing method of the present invention, the mold having the fixed part and the moving part is used and synthetic resin material containing foaming agent or foaming gas is injected into the cavity. At this time, the moving part which opposes the ordinary portion is kept in its advancing state so as to minimize the volume of the cavity.

Next, after the injection of the synthetic resin material is completed, the moving part is retracted to increase the volume of the ordinary portion in the cavity. Accompanied by this, the synthetic resin material containing the foaming agent or foaming gas begins to foam in the ordinary portion due to pressure produced when the foaming agent or foaming gas expands. Meanwhile, according to the present invention, the temperature of a mold portion adjoining the moving part is kept higher than that of the moving part. Thus, likeliness of foaming of material itself in contact with the mold is higher in material of the joining flat surface forming portion kept at high temperatures. Thus, accompanied by flow of the material, foaming in the joining flat surface forming portion is urged at the same time.

Consequently, entirely substantially uniform foaming condition can be obtained due to likeliness of foaming by increased volume and foaming under high temperatures.

Then, due to substantially uniform foaming pressure, generation of sink mark at the time of molding can be suppressed so that the obtained appearance characteristic can be improved.

In the foamed molded product, the joining flat surface forming portion having the joining flat surface is formed without changing its volume. As a result, a sufficient flatness of the joining flat surface can be obtained, thereby improving the bonding performance to a joining object.

BRIEF DESCRIPTION OF THE DRAWINGS

A more complete appreciation of the invention and many of the attendant advantages thereof become readily apparent with reference to the following detailed description, particularly when considered in conjunction with the accompanying drawings, in which:

FIG. 1 is a sectional partially perspective view of a foamed molded product of the first embodiment;

FIG. 2 is an explanatory diagram showing the structure of an injection unit and mold of the first embodiment;

FIG. 3 is an explanatory diagram showing a state in which a mold is filled with synthetic resin in the first embodiment;

FIG. 4 is an explanatory diagram showing a state in which the moving part of the mold is retracted in the first embodiment;

FIG. 5 is an explanatory diagram showing a state in which a foamed molded product is released from the mold in the first embodiment;

FIG. 6 is an explanatory diagram showing a state in which the mold is closed in the first embodiment;

FIG. 7 is a sectional partially perspective view of the foamed molded product of the second embodiment;

FIG. 8 is an explanatory diagram showing a state in which the mold is filled with synthetic resin material in the second embodiment;

FIG. 9 is an explanatory diagram showing a state in which the moving part of the mold is retracted in the second embodiment;

FIG. 10 is an explanatory diagram showing a state in which a foamed molded product is released from the mold in the second embodiment;

FIG. 11 is an explanatory diagram showing a state in which the mold is closed in the second embodiment;

FIG. 12 is a sectional partially perspective view of a foamed molded product of the third embodiment;

FIG. 13 is a sectional partially perspective view of a foamed molded product of the fourth embodiment;

FIG. 14 is a sectional partially perspective view of a foamed molded product of the fifth embodiment;

FIG. 15 is an explanatory diagram showing the structure of an injection unit and mold of the fifth embodiment;

FIG. 16 is an explanatory diagram showing a state in which the mold is filled with synthetic resin material in the fifth embodiment;

FIG. 17 is an explanatory diagram showing a state in which the moving part of the mold is retracted in the fifth embodiment;

FIG. 18 is an explanatory diagram showing a state in which a foamed molded product is released from the mold in the fifth embodiment;

FIG. 19 is an explanatory diagram showing a state in which the mold is closed in the fifth embodiment;

FIG. 20 is an explanatory diagram showing a state in which the mold is filled with synthetic resin material in the sixth embodiment;

FIG. 21 is an explanatory diagram showing a state in which the moving part of the mold is retracted in the sixth embodiment;

FIG. 22 is an explanatory diagram showing a state in which a foamed molded product is released from the mold in the sixth embodiment;

FIG. 23 is an explanatory diagram showing a state in which the mold is closed in the sixth embodiment;

FIG. 24 is an explanatory diagram showing the structure of an injection unit and mold of the seventh embodiment;

FIG. 25 is an explanatory diagram showing a state in which the mold is filled with synthetic resin material in the seventh embodiment;

FIG. 26 is an explanatory diagram showing a state in which the moving part of the mold is retracted in the seventh embodiment;

FIG. 27 is an explanatory diagram showing a state in which a foamed molded product is released from the mold in the seventh embodiment;

FIG. 28 is an explanatory diagram showing a state in which the mold is closed in the seventh embodiment;

FIG. 29 is an explanatory diagram showing a state in which the mold is filled with synthetic resin material in the eighth embodiment;

FIG. 30 is an explanatory diagram showing a state in which the moving part of the mold is retracted in the eighth embodiment;

FIG. 31 is an explanatory diagram showing a state in which a foamed molded product is released from the mold in the eighth embodiment;

FIG. 32 is an explanatory diagram showing a state in which the mold is closed in the eighth embodiment;

FIG. 33 is a sectional partially perspective view of a foamed molded product of the ninth embodiment;

FIG. 34 is an explanatory diagram showing the structure of an injection unit and mold of the ninth embodiment;

FIG. 35 is an explanatory diagram showing a state in which the mold is filled with synthetic resin material in the ninth embodiment;

FIG. 36 is an explanatory diagram showing a state in which the moving part of the mold is retracted in the ninth embodiment;

FIG. 37 is an explanatory diagram showing a state in which a foamed molded product is released from the mold in the ninth embodiment;

FIG. 38 is an explanatory diagram showing a state in which the mold is closed in the ninth embodiment;

FIG. 39 is an explanatory diagram showing a state in which the mold is filled with synthetic resin material in the tenth embodiment;

FIG. 40 is an explanatory diagram showing a state in which the moving part of the mold is retracted in the tenth embodiment;

FIG. 41 is an explanatory diagram showing a state in which a foamed molded product is released from the mold in the tenth embodiment;

FIG. 42 is an explanatory diagram showing a state in which the mold is closed in the tenth embodiment;

FIG. 43 is a sectional partially perspective view of a foamed molded product of the eleventh embodiment;

FIG. 44 is a sectional partially perspective view of a foamed molded product of the twelfth embodiment; and

FIG. 45 is a sectional partially perspective view of a foamed molded product of a conventional example.

DESCRIPTION OF THE PREFERRED EMBODIMENTS

In the foamed molded product of the first aspect of the present invention, as described above, the foaming ratios of a joining flat surface forming portion and ordinary portion are made positively different. The joining flat surface forming portion mentioned here refers to a portion in which the joining flat surface is provided. More specifically, a portion gained by projecting the joining flat surface in the thickness direction can be called the joining flat surface forming portion. At this time, if ribs for restricting the disposition position of a joining material such as double-sided adhesive tape are provided on an end or both ends of the joining flat surface, this rib or the like can be considered to be part of the aforementioned joining flat surface forming portion.

Further, the ordinary portion refers to other portion than the joining flat surface forming portion.

If the boundary between the joining flat surface forming portion and the ordinary portion is not clear, a local foaming ratio of a portion which can be recognized clearly to be the joining flat surface forming portion, for example, a portion adjoining the central portion of the joining flat surface can be made to represent the foaming ratio of the joining flat surface forming portion and a local foaming ratio of a portion which can be recognized clearly to be an ordinary portion, and a portion sufficiently away from the joining flat surface can be made to represent the foaming ratio of the ordinary portion.

It is preferable that the joining flat surface forming portions are provided on an end or both ends of the ordinary portion. For example, if the joining flat surface portions are provided on the both ends of the ordinary portion, as described later, the ordinary portion can be formed in a substantially arcuate shape such that it is floated from the joining flat surface. The substantially arcuate shape mentioned here includes a substantially U shape and a substantially mountain-like shape and is a concept including various shapes in which any portion between the both ends is floated. Further, the ordinary portion may be provided substantially flush with the joining flat surface without being floated. Further, the joining flat surface may be provided on only a single end of the ordinary portion. In this case also, it is permissible to float the ordinary portion from the joining flat surface so that its entire configuration is formed in a substantially L shape or the ordinary portion may be substantially flush with the joining flat surface without being floated.

Particularly, it is preferable that the foamed molded product comprises an arch portion as the ordinary portion whose sectional shape is substantially arcuate, and the joining flat surfaces provided on both ends of a concave side face of the arch portion. In this case, it is effective to provide with a difference in the foaming ratio. The substantially arcuate arch portion mentioned here includes various shapes in which any portion between the both ends is floated such as a substantially U shape and a substantially mountain-like shape.

Further, preferably, when the foaming ratio of the joining flat surface forming portion is assumed to be A and the foaming ratio of the ordinary portion is assumed to be B, B/A=1.01-2.5. If the B/A is less than 1.01, no sufficient effect due to increasing of the foaming ratio of the ordinary portion more than the joining flat surface forming portion can be obtained. On the other hand, if the B/A exceeds 2.5, often the strength of a product cannot be obtained or foamed layer appears on the surface, thereby not satisfying appearance characteristic.

As a method for measuring the foaming ratio, for example, it can be calculated by measuring the densities of the joining flat surface forming portion and the ordinary portion. Although in this case, the boundary between the joining flat surface forming portion and the ordinary portion is clear, the foaming ratios can be calculated using the entire portion of each of these, if the boundary portion is not clear, a portion securely included in the joining flat surface forming portion and a portion securely included in the ordinary portion are used as each representative portion so as to obtain the foaming ratio of each portion for comparison.

Further, it is preferable that the foamed molded product further comprises a groove portion which is dented from the same side face as a face provided with the joining flat surface, the groove formed between the joining flat surface forming portion and the ordinary portion.

In this case, by adopting a structure for forming the groove portion between the ordinary portion and the joining flat surface forming portion, the foaming ratio can be controlled stably at the time of manufacturing.

It is preferable that the foamed molded product is a side molding to be joined to an automobile body. A configuration having the arch portion while having the joining flat surface on its rear side is suitable for the side molding and an effect of the configuration whose foaming ratios are controlled is very significant.

According to a second aspect of the present invention, it is preferable that the mold comprises a movable part provided with the moving part capable of advancing/retracting relatively so that the movable part and the fixed part are capable of advancing/retracting relative to each other. In this case, an ordinary mold structure in which the fixed part and the movable part are combined is used and then, the moving part is incorporated in the movable part. Meanwhile, it is permissible to adopt a structure in which the movable part and the moving part are integrated (see the second embodiment). In this case, its entire structure may be called movable part or moving part and at least, a portion capable of advancing/retracting with respect to the fixed part at the time of molding and of accelerating the foaming of the ordinary portion corresponds to the moving part.

It is preferable that the mold comprises an eject part for releasing the foamed molded product after molding and the joining surface forming cavity face is provided at the front end face of the eject part. In this case, the eject part takes roles as so-called eject pin and the joining surface forming cavity face at the same time, thereby rationalizing the structure of the mold.

It is preferable that the foamed molded product has an arch portion whose sectional shape is substantially arcuate, the joining flat surfaces are provided on both ends of a concave side face of the arch portion and the moving part is disposed such that it is sandwiched by two joining surface forming cavity faces. The moving part is preferred to be disposed so that it is sandwiched by the two joining surface forming cavity faces. In this case, particularly, the operation and effect of the above-described manufacturing method are effective.

Further, it is preferable that the manufacturing method of foamed molded product comprises filling the cavity with preliminary pressurizing gas to provide with preliminary pressure prior to the injecting. In this case, when the synthetic resin material is injected to the cavity, a pressure called counter pressure is applied to the synthetic resin material by the preliminary pressure of the preliminary pressurizing gas. Thus, even if it is injected with a relatively low pressure, the injected synthetic resin material is pressurized appropriately. Consequently, portion near the outer periphery of a molded product is hardened in solid state as skin layer finally, thereby improving the appearance characteristic.

It is preferable that the foamed molded product in which groove portions dented from the same face as a face provided with the joining flat surfaces are formed between the joining flat surface forming portion and the ordinary portion, and wherein the mold includes a projecting portion for forming the groove portion formed on a boundary between the joining surface forming cavity face and the moving part.

In this case, the joining surface forming cavity face has the protruded portion at the boundary on the moving part. As a result, even after the moving part is retracted, the protruded portion takes a role of weir, preventing material located at the joining flat surface forming portion from being moving toward the ordinary portion easily. Thus, a position where foaming occurs can be concentrated on the ordinary portion so that a difference in foaming ratio can be produced clearly.

In the meantime, the material located at the joining flat surface forming portion also try to foams lightly in such a manner to release a pressure from a portion without any weir to the ordinary portion. Consequently, generation of sink mark at the time of molding can be suppressed by the pressure of the foaming thereby leading to improvement in the appearance characteristic.

The joining flat surface forming portion of an obtained foamed molded product is formed in a low foaming condition without changing its volume at the time of molding. Thus, flatness of the joining flat surface provided on the joining flat surface forming portion can be secured sufficiently, thereby improving the bonding performance to a joining object.

As foaming agent to be contained by the synthetic resin material, NaHCO₃ (sodium hydrogen carbonate) or other various kinds of materials can be applied.

Further, as foaming gas to be contained by the synthetic resin material, for example, carbon dioxide (CO₂), nitrogen (N₂) or other inactive gas can be used.

As the preliminary pressurizing gas for providing the counter pressure, air or the same gas as the above-mentioned foaming gas can be applied.

The preliminary pressure to be applied by the preliminary pressurizing gas is preferred to be in a range of 0.1-1.0 MPa. If the preliminary pressure is less than 0.1 MPa, no sufficient counter pressure can be applied and on the other hand, if it exceeds 1.0 MPa, the foaming is suppressed.

As the synthetic resin material, for example, various synthetic resins such as thermoplastic olefin (TPO) resin represented by polypropylene (PP) and polyolefin base thermoplastic elastomer can be applied. Additionally, it is permissible to add foaming nucleating agent such as Na₂CO₃ to these.

It is preferable that the moving part is kept at a temperature higher than at least the joining surface forming cavity face. In this case, material of the ordinary portion opposing the moving part can be heated to a temperature higher than the joining flat surface forming portion so that foaming is likely to occur and thus, the ordinary portion can be introduced into a higher foaming condition convergently.

Although the range of preferred temperatures for the moving part differs depending on the kind of the synthetic resin material, it is in a range of 20-60° C. On the other hand, portions other than the moving part is preferred to be maintained in a range of 30-80° C.

It is preferable that between the moving part and a mold part adjacent thereto, a heat insulating structure for reducing heat transmission between the both is provided and with the moving part kept at a temperature higher than other portions, synthetic resin material containing foaming agent or synthetic resin material containing foaming gas is injected into the cavity and after that, by retracting the moving part, the volume of the ordinary portion is increased in volume to urge the foaming. In this case, the heat insulating structure is provided between the moving part and the adjoining mold portion to reduce heat transmission between the both and the moving part is maintained at a temperature higher than the other mold portion. That high temperature condition can be maintained with a large difference in temperature with respect to the adjoining mold portion by the operation of the above-described heat insulating structure. Thus, the material of the ordinary portion can be kept at a temperature higher than the material of the joining flat surface forming portion so that foaming is likely to occur and therefore, the convergent foaming can be urged further.

As the heat insulating structure which can be applied, for example, there is a structure in which a heat insulating material is interposed on a sliding face between the moving part and the adjoining mold portion.

Although as the heat insulating material of this case, various kinds of well known heat insulators can be used, for example, thermosetting resin such as phenol resin is available.

The foamed molded product according to a third aspect of the present invention, it is preferable that the joining flat surface forming portions are provided on an end or both ends of the ordinary portion. For example, in case of the structure in which the joining flat surfaces are provided on both ends of the ordinary portion, as described later, the ordinary portion can be formed in a substantially arcuate shape by retracting it from the joining flat surface. The substantially arcuate shape mentioned here is a concept including a substantially U shape, a substantially mountain-like shape and various shapes in which any portion between the both ends is floated. Further, the joining flat surface may be provided on only a single end of the ordinary portion. In this case, the entire shape may be formed into a substantially L shape by retracting the ordinary portion from the joining flat surfaces.

It is preferable that the foamed molded product comprises an arch portion as the ordinary portion whose sectional shape is substantially arcuate, and the joining flat surfaces provided on both ends of the concave side face of the arch portion. In this case, it is effective to provide with a difference in foaming ratio. The substantially arcuate arch portion mentioned here includes a substantially U shape, a substantially mountain-like shape and various shapes in which any portion between both ends is floated (retreated).

Preferably, when the foaming ratio of the joining flat surface forming portion is assumed to be A and the foaming ratio of the ordinary portion is assumed to be B, B/A=0.90-1.10. If the B/A is out of this range, there occurs a deterioration due to a difference in foaming ratio between the joining flat surface forming portion and the ordinary portion. By confining to this range, it is easy to obtain foaming ratio of more than 1.2 times for both A and B. For the reason, generation of sink mark at the time of molding can be suppressed securely. Then, it is possible to obtain a foamed molded product having a uniform and high foaming ratio.

As a method for measuring the foaming ratio, for example, it can be calculated by measuring the densities of the joining flat surface forming portion and the ordinary portion.

It is preferable that the foamed molded product is a side molding to be joined to an automobile body. A configuration having the arch portion while having the joining flat surface on its rear side is suitable for the side molding and an effect of the configuration whose foaming ratios are controlled is very significant.

According to the fourth aspect of the present invention, it is preferable that the mold comprises a movable part provided with the moving part capable of advancing/retracting relatively so that the movable part and the fixed part are capable of advancing/retracting relative to each other. In this case, an ordinary mold structure in which the fixed part and the movable part are combined is used and then, the moving part is incorporated in the movable part. Meanwhile, it is permissible to adopt a structure in which the movable part and the moving part are integrated (see the second embodiment). In this case, its entire structure may be called movable part or moving part and at least, a portion capable of advancing/retracting with respect to the fixed part at the time of molding and of accelerating the foaming of the ordinary portion corresponds to the moving part.

Further, it is preferable that the mold comprises an eject part for releasing the foamed molded product after molding and the joining surface forming cavity face is provided at the front end face of the eject part. In this case, the eject part takes roles as so-called eject pin and the joining surface forming cavity face at the same time, thereby rationalizing the structure of the mold.

Further, it is preferable that the manufacturing method of foamed molded product comprises filling the cavity with preliminary pressurizing gas to provide with preliminary pressure prior to the injecting. In this case, when the synthetic resin material is injected into the cavity, a pressure called counter pressure is applied to the synthetic resin material by the preliminary pressure of the preliminary pressuring gas. For the reason, even if it is injected at a relatively low pressure, the injected synthetic resin material is pressurized appropriately. Consequently, portions near the outer periphery of a molded product are hardened in a solid state as so-called skin layer finally thereby improving its appearance characteristic.

As the foaming agent to be contained in the synthetic resin material, NaHCO₃ (sodium hydrogen carbonate), azodicarbonamide and other various kinds of materials can be applied.

Further, as the foaming gas to be contained in the synthetic resin material, for example, carbon dioxide (CO₂), nitrogen (N₂) and other inactive gases can be used.

As the preliminary pressurizing gas for applying the counter pressure, air or the same gas as the foaming gas can be applied.

The preliminary pressure to be applied by the preliminary pressurizing gas is preferred to be in a range of 0.1-1.0 Mpa. If the preliminary pressure is less than 0.1 MPa, no sufficient counter pressure can be applied and on the other hand, if it exceeds 1.0 MPa, the foaming is suppressed.

As the synthetic resin material, for example, various synthetic resins such as thermoplastic olefin (TPO) resin represented by polypropylene (PP) and polyolefin base thermoplastic elastomer can be applied. Additionally, it is permissible to add foaming nucleating agent such as Na₂CO₃ to these.

As the heat insulating structure which can be applied to the manufacturing method of the fourth aspect, for example, there is a structure in which a heat insulating material is interposed on a sliding face between the moving part and the adjoining mold portion.

Although as the heat insulating material of this case, various kinds of well known heat insulators can be used, for example, thermosetting resin such as phenol resin is available.

EMBODIMENTS Embodiment 1

The foamed molded product of the embodiment of the present invention and its manufacturing method is described with reference to FIGS. 1-6.

The foamed molded product 1 of this embodiment is a foamed molded product having a joining flat surface 15 to be joined to a joining object as shown in FIG. 1.

The foaming ratio of an ordinary portion 11, is higher than the foaming ratio of a joining flat surface forming portion 12, which is provided with the joining flat surface 15.

Hereinafter, this is described further in detail.

The foamed molded product 1 has an arch portion 10 whose sectional shape is substantially arcuate and the joining flat surfaces 15 are provided on both ends of a face having a concave portion of the arch portion 10. The foaming ratio of an ordinary portion 11 sandwiched by a joining flat surface forming portions 12, is higher than the foaming ratio of the joining flat surface forming portion 12, which is a portion gained by projecting the joining flat surface 15 on the both ends of the arch portion 10 in the thickness direction.

As for specific foaming ratio, when the foaming ratio of the joining flat surface forming portion is assumed to be A and the foaming ratio of the ordinary portion is assumed to be B, B/A is adjusted to fall under a range of 1.01-2.5.

As shown in FIG. 1, thin film-like skin layer 19, in which foaming occurs little, is formed on the entire outer peripheral face of the arch portion 10.

The foamed molded product 1 of this embodiment is a side molding to be joined to an automobile body and double-sided adhesive tape is bonded to the joining flat surface 15, by which that foamed molded product is joined to the automobile body, which is a joining object.

Next, a manufacturing method of the foamed molded product 1 is described.

In this embodiment, as shown in FIG. 2, an injection unit 5 containing a screw 51 and a foaming agent introducing portion 54 for introducing foaming agent is employed.

A mold 6 is connected to the front end of the injection unit 5.

As shown in FIG. 2, the mold 6 of this embodiment includes a fixed part 62 and a moving part 615 which advances/retracts with respect to the fixed part 62. Further, the mold 6 includes a movable part 61 provided with the moving part 615 such that it is capable of advancing/retracting relatively and the movable part 61 and the fixed part 62 are capable of advancing/retracting with respect to each other.

The mold 6 has a pair of eject parts 612 for releasing the foamed molded product 1 after molding is completed and a joining surface forming cavity face 82 is provided on the front end face of the eject parts 612. This eject parts 612 are capable of advancing/retracting with respect to the moving part 615.

That is, the movable part 61 includes a main body portion 610, a pair of the eject parts 612, right and left, having the joining surface forming cavity faces 82 for forming the two joining flat surfaces 15 and the moving part 615 disposed such that it is sandwiched by these, as shown in the same Figure.

The moving part 615 is disposed to oppose only the ordinary portion 11 in the concave side face of the arch portion 10 and constructed to be capable of advancing/retracting with respect to the main body portion 610 by an actuator (not shown).

According to this embodiment, a cavity 8 for forming the foamed molded product 1 is formed by the fixed part 62, the moving part 615 and the eject parts 612.

The eject parts 612 are capable of advancing/retracting with respect to the main body portion 610 by an actuator (not shown). However, as described later, this functions at the time of releasing a completed product from the mold, on the other hand, the eject parts remain integrated with the main body portion 610 at the time of molding.

The fixed part 62 is a mold having a cavity face 81 corresponding to the entire convex side of the arch portion 10 and when the mold is opened, it leaves the movable part 61 by a relative moving of the movable part 61 and when the mold is closed, it approaches the movable part 61 by the moving of the movable part 61.

When the foamed molded product 1 is manufactured using the mold 6 and the injection unit 5 having the above-described structure, first, as shown in FIG. 2, the movable part 61 and the fixed part 62 are matched and tightened together and by advancing the moving part 615, the volume of the cavity 8 is minimized. Additionally, the cavity 8 is filled with air as preliminary pressurizing gas through a path (not shown) so as to provide with the preliminary pressure.

In the injection unit 5, NaHCO₃ as foaming agent is introduced into synthetic resin material and these components are kneaded and advanced along a screw 51. In this embodiment, PP is used as synthetic resin material and Na₂CO₃ (sodium carbonate) generated by thermal decomposition of NaHCO₃ is used as foaming nucleating agent.

When injection is carried out into the cavity 8 from the injection unit 5, appropriate counter pressure is applied to injected synthetic resin material by the preliminary pressurizing gas charged into the cavity 8. Consequently, the synthetic resin material fills the cavity 8 while so-called skin layer 19 (FIG. 1) is formed on the outer surface of the molded product.

After the cavity 8 is filled with the injected synthetic resin material 100 as shown in FIG. 3, the moving part 615 is retracted as shown in FIG. 4. Consequently, the volume of the ordinary portion in the cavity 8 is increased largely. Thus, the synthetic resin material 100 containing the foaming agent is foamed convergently in the ordinary portion 11 by a pressure produced by expanding foaming agent. The material located at the joining flat surface forming portion 12 is more or less foamed to release the pressure toward the ordinary portion 11.

By these foamings, as shown in FIG. 1, a structure in which the foaming ratio of the ordinary portion 11 sandwiched by the joining flat surface forming portions 12 is higher than the foaming ratio of the joining flat surface forming portion 12 is obtained. The arch portion 10 is constructed that its entire outer peripheral face is covered with thin film-like skin layer 19 in which foaming occurs little.

Pressure at the time of foaming suppresses generation of sink mark at the time of molding thereby providing an excellent appearance characteristic.

The eject parts 612 provided with the joining surface forming cavity face 82 for forming the joining flat surface 15 keep its constant position during molding. The joining flat surface forming portion 12 opposing this face is molded in a low foaming condition. Thus, the joining flat surface 15 is finished in a very flat condition by transferring the smoothness of the joining surface forming cavity face 82 faithfully. Thus, when double-sided adhesive tape and the like is bonded to this joining flat surface 15 and then, this foamed molded product is bonded to an automobile body, its bonding performance can be obtained sufficiently.

After the molding is completed, as shown in FIG. 5, the movable part 61 and the fixed part 62 are separated from each other to open the mold and by advancing the eject parts 612 from the main body portion 610, the foamed molded product 1 is released from the mold.

After that, as shown in FIG. 6, to prepare for molding of a next product, the eject parts 612 are returned to its original position and the movable part 61 and the fixed part 62 are matched and tightened together. Then, after the state of FIG. 2 is regained by advancing the moving part 615 again, the above-described series of molding operation are performed repeatedly so as to mold the foamed molded product 1 continuously.

In this embodiment, the mold 6 provided with the moving part 615 opposing only the rear face of the ordinary portion 11 is utilized and it is retracted after the synthetic resin material 100 containing foaming agent is injected into the cavity 8. At the same time when this moving part 615 is retracted, foaming can be accelerated in mainly the ordinary portion 11, so that the foamed molded product 1 having the above-described structure can be obtained easily.

In the foamed molded product 1 obtained in this embodiment, as described above, the foaming ratio of the ordinary portion 11 is lower than the foaming ratio of the joining flat surface forming portion 12 and the joining flat surface forming portion 12 is maintained at a low foaming ratio or in a nearly solid state. Consequently, the joining flat surface forming portion 11 having the joining flat surface 15 has a high rigidity and an excellent stability in configuration. Thus, when it is bonded to a joining object, stable joining condition is obtained. Further, the smoothness of the joining flat surface 15 can be improved so that adhesiveness to an adhesive member such as double-sided adhesive tape is intensified, thereby improving the bonding performance.

Further, because the foaming ratio of the ordinary portion 11 is kept high, deterioration of the appearance due to sink mark can be prevented at the time of manufacturing.

Further, by replacing the conventional solid product with the foamed molded product 1 of this embodiment, the adhesiveness to a bonding object can be raised and reduction in cost due to decreased weight and reduction of use materials can be achieved.

According to this embodiment, foaming agent is contained in synthetic resin material and foaming of this foaming agent (so-called chemical foaming) is adopted. Instead, it is permissible to adopt foaming with foaming gas (so-called physical foaming) by making carbon dioxide or the like contained in synthetic resin material as foaming gas. This point is common to all embodiments described below.

Embodiment 2

In this embodiment, as shown in FIGS. 8-11, instead of the mold 6 of the first embodiment, a mold 7 having a more or less different structure is used. Further, as shown in FIG. 7, the shape of a foamed molded product 102 of a molding object is not an arcuate shape having the concave portion but a shape whose rear face is substantially flat. Then, joining flat surfaces 152 and joining flat surface forming portions 122 are provided on both ends in the width direction and a portion sandwiched by these is an ordinary portion 112.

The mold 7 used for this embodiment, as shown in FIGS. 8-11, includes a fixed part 72 and a movable part 71 provided with a moving part 715 integrally which advances/retracts with respect to the fixed part 72. There is provided a cavity 8 for forming a foamed molded product between these.

As shown in FIG. 8, the movable part 71 has a main body portion 710 and a pair of eject parts 712, right and left, having joining surface forming cavity faces 82 for forming the two joining flat surfaces 15. Then, a moving part 715 protruded to oppose only the ordinary portion 112 is formed integrally in the center of the main body portion 710. That is, according to this embodiment, the main body portion 710 including the moving part 715 is advanced or retracted relatively to achieve moving of the moving part 715.

The front end face (cavity face) of the moving part 715 is provided on a flat surface and when the moving part 715 is protruded, it is protruded forward of the joining surface forming cavity face 82 and when the moving part 715 is retracted, it is set flush with the joining surface forming cavity face 82.

The aforementioned eject parts 712 are the same as the eject parts 612 of the first embodiment as shown in FIG. 8.

The other structure of the mold 7 is the same as the first embodiment.

When the foamed molded product 102 is produced using the mold 7 having the above-described structure and the injection unit 5, first, as shown in FIG. 8, the movable part 71 and the fixed part 72 are matched and tightened together to close the mold and additionally, by advancing the main body portion 710 including the moving part 715, the volume of the cavity 8 is minimized. The cavity 8 is charged with air as the preliminary pressuring gas to provide with preliminary pressure through a path (not shown). Then, synthetic resin material 100 fills the cavity 8 in the same way as the first embodiment.

After that, as shown in FIG. 9, with the eject parts 712 left, the main body portion 710 including the moving part 715 is retracted. Consequently, the volume of the ordinary portion in the cavity 8 is increased largely. Thus, foaming is generated convergently in the ordinary portion 112.

Although material located at the joining flat surface forming portion 122 tends to generate foaming more or less to release pressure toward the ordinary portion 112, the foaming ratio is extremely lower than that of the ordinary portion 112.

According to this embodiment, the rear face of the foamed molded product 102 is a flat surface without any concavity and the rear face of the ordinary portion 112 is substantially flush with the joining flat surfaces 152 (see FIG. 7).

After molding is completed, as shown in FIG. 10, the movable part 71 and the fixed part 72 are separated to open the mold and additionally, the eject parts 712 are advanced largely from the main body portion 710 to release the foamed molded product 102 from the mold.

After that, as shown in FIG. 11, to mold a next product, the eject parts 712 are returned to its original position and at the same time, the movable part 71 and the fixed part 72 are matched and tightened together. Then, after the state of FIG. 8 is regained, the above-described series of molding operations are repeated, so that the foamed molded products 102 can be molded continuously.

The same operation and effect as the first embodiment are obtained.

Embodiment 3

This embodiment shows a first modification in which the shape of the foamed molded product of the present invention is modified. A foamed molded product 2 of a first modification includes, as shown in FIG. 12, an arch portion 20 and an ornament portion 28 adjoining an end thereof.

The arch portion 20 of this foamed molded product 2 has joining flat surfaces 25 to be bonded to a joining object on both ends of the concave side face of the arch portion 20. Then, the foaming ratio of the ordinary portion 21 sandwiched by the joining flat surface forming portions 22 is set higher than the foaming ratio of the joining flat surface forming portion 22 which is erected from a joining flat surface 25 on each of both ends of the arch portion 20.

To manufacture a foamed molded product 2, a mold (not shown) having a cavity for forming the arch portion 20 and an ornament cavity for forming the ornament portion 28 is used and the same operation as the first embodiment is carried out for the cavity portion. Consequently, the foaming ratios of the ordinary portion and the joining flat surface forming portion can be controlled in the same manner as the first embodiment. Other matters are the same as the first embodiment.

Embodiment 4

This embodiment shows a second modification in which the shape of the foamed molded product of the present invention is modified.

The foamed molded product 3 of the second modification includes, as shown in FIG. 13, a first arch portion 310, a second arch portion 320 and an ornament portion 38 adjoining between these.

The first arch portion 310 of this foamed molded product 3 has joining flat surfaces 351, 352 to be bonded to a joining object on both ends of a concave side face of the first arch portion 310. The foaming ratio of an ordinary portion 311 sandwiched by the joining flat surface forming portions 312, 313 is set higher than the foaming ratio of the joining flat surface forming portions 312, 313 erected from the joining flat surfaces 351, 352 on the both ends of the first arch portion 310.

The joining flat surface 351 is tilted to correspond to the shape of a joining object (not shown) and rib portions 36 for restricting the position of double-sided adhesive tape 99 are formed on both sides protrudedly.

Meanwhile, the joining flat surface 352 is permitted to be a simple flat surface not to be joined to any joining object or a part of the ordinary portion.

Likewise, the second arch portion 320 has joining flat surfaces 353, 354 to be joined to the joining object on both ends of the concave side face of the second arch portion 320. Then, the foaming ratio of an ordinary portion 321 sandwiched by the joining flat surface forming portions 322, 323 is set higher than the foaming ratio of the joining flat surface forming portions 322, 323 erected from the joining flat surfaces 353, 354 on both ends of the second arch portion 320.

The joining flat surface 354 forms protruded rib portions 36 for restricting the position of the double-sided adhesive tape 99 on both sides.

The joining flat surface 353 is permitted to be a simple flat surface not to be joined to any joining object or a part of the ordinary portion.

To manufacture the foamed molded product 3, there is used a mold (not shown) having eject parts having a joining surface forming cavity face containing concave portions for forming the rib portions 36 and then having two cavities for forming the first arch portion 310 and the second arch portion 320 and an ornament cavity for forming the ornament portion 38, and the same operation as the first embodiment is carried out for the two cavity portions. Consequently, the foaming ratios of the ordinary portion and the joining flat surface forming portions can be controlled in the same manner as the first embodiment.

The others are the same as the first embodiment.

As a method for adjusting the foaming ratio of the ordinary portion and the joining flat surface forming portion in all the above-described embodiments, it is permissible to adopt methods by adjusting timing (core back timing) for retracting the moving part after synthetic resin material is injected into the cavity or the amount of retraction (core back amount) of the moving part or adjusting the temperature of respective parts constituting the mold.

Embodiment 5

The foamed molded product and the manufacturing method of this embodiment is described with reference to FIGS. 14-19.

A foamed molded product 105 of this embodiment is a foamed molded product having a joining flat surface 15 to be joined to a joining object as shown in FIG. 14.

The foaming ratio of an ordinary portion 11 adjacent to a joining flat surface forming portion 12 is higher than the foaming ratio of the joining flat surface forming portion 12 which is a portion gained by projecting the joining flat surface 15 substantially vertically. There are groove portions 18, which are dented from the same side as a face provided with the joining flat surfaces 15, between the joining flat surface forming portion 12 and the ordinary portion 11.

Hereinafter, this is described further in detail.

The foamed molded portion 105 has an arch portion 10 whose sectional shape is substantially arcuate and the joining flat surfaces 15 are provided on both ends of the concave side face of the arch portion 10. Then, the foaming ratio of the ordinary portion 11 sandwiched by the joining flat surface forming portions 12 is higher than the foaming ratio of the joining flat surface forming portion 12 erected from the joining flat surfaces 15 on both ends of the arch portion 10.

As for a specific foaming ratio, when the foaming ratio of the joining flat surface forming portion is assumed to be A and the foaming ratio of the ordinary portion is assumed to be B, B/A is adjusted so as to fall under a range of 1.01-2.5.

The groove portions 18, which are dented from the concave side face (rear face) of the arch portion 10, are provided between the ordinary portion 11 and the joining flat surface forming portion 12.

As shown in the same Figure, the foamed molded product 105 of this embodiment has ornamental lines 19 at portions corresponding to the groove portions 18 in the surface of the arch portion 10. Consequently, even if slight sink mark occurs, the ornamental line 19 protects the appearance from any problem.

As shown in FIG. 14, thin film-like skin layer 19 in which foaming is generated little is formed on the entire outer peripheral face of the arch portion 10.

The foamed molded product 105 of this embodiment is a side molding to be bonded to an automobile body and configured to be bonded to the automobile body as a joining object using the double-sided adhesive tape on the joining flat surfaces 15.

Next, the method for manufacturing the foamed molded product 105 is described.

According to this embodiment, as shown in FIG. 15, as an injection unit 5, a unit incorporating a screw 51 and having a foaming agent introducing portion 54 for introducing foaming agent is used.

A mold 605 is connected to the front end of the injection unit 5.

As shown in FIG. 15, the mold 605 of this embodiment has a movable part 61 and a fixed part 62 and there is provided a cavity 8 for forming the foamed molded product 105 between these.

As shown in the same Figure, the movable part 61 includes a main body portion 610, a pair of eject parts 612, right and left, each having a joining surface forming cavity face 82 for forming each of the two joining flat surfaces 15 and a moving part 615 disposed such that it is sandwiched thereby.

The moving part 615 is disposed so as to oppose only the ordinary portion 11 on the concave side face of the arch portion 10 and constructed to be capable of advancing/retracting with respect to the main body portions 610 by an actuator (not shown).

Then, a cavity 8 for forming the foamed molded product 105 is formed by the fixed part 62, the moving part 615 and the eject parts 612.

As shown in the same Figure, the eject part 612 has a projecting portion 825 for forming the groove portion 18 on a boundary between the joining surface forming cavity face 82 for forming the joining flat surface 15 and the moving part 615.

The eject part 612 is capable of advancing with respect to the main body portion 610 by an actuator (not shown). However, this function at the time of releasing a molded product as described later, on the other hand, the eject part 612 remain integrated with the main body portion 610 at the time of molding.

The fixed part 62 is a mold having a cavity face 81 corresponding to the entire convex side face of the arch portion 10 and when the mold is opened, it leaves the movable part 61 by moving of the movable part 61 and when the mold is closed, it approached the movable part 61.

According to this embodiment, a heater (not shown) is built-in the moving part 615 so as to adjust the temperature by heating to always maintain a temperature of over 50° C. On the other hand, other portions than the moving part 615 is not heated for temperature adjustment and always kept at a temperature below that of the moving part 615.

Upon manufacturing the foamed molded product 105 using the mold 605 and the injection unit 5 having the above-described structure, as shown in FIG. 15, the movable part 61 and the fixed part 62 are matched and tightened together and further, by advancing the moving part 615, the volume of the cavity 8 is minimized. The cavity 8 is filled with air as preliminary pressurizing gas through a path (not shown) so as to provide with preliminary pressure.

In the injection unit 5, NaHCO₃ as foaming agent is introduced into synthetic resin material and kneaded and then, these kneaded substances are advanced along a screw 51. Meanwhile, according to this embodiment, PP is used as synthetic resin material and Na₂CO₃ (sodium carbonate) generated from thermal decomposition of NaHCO₃ is used as foaming nucleating agent.

When injection is carried out from the injection unit 5 to the cavity 8, appropriate counter pressure is applied to the injected synthetic resin material by the preliminary pressurizing gas charged into the cavity 8. Consequently, the synthetic resin material fills the cavity 8 while so-called skin layer 19 (FIG. 14) is formed on the outer surface of the molded product.

After the cavity 8 is filled with the injected synthetic resin material 100 as shown in FIG. 16, the moving part 615 is retracted as shown in FIG. 17. Consequently, the volume of the ordinary portion in the cavity 8 is increased largely.

As shown above, the mold 605 of this embodiment has the projecting portion 825 on a boundary between the joining surface forming cavity face 82 and the moving part 615. Thus, even after the moving part 615 is retracted, the projecting portion 825 takes a role of so-called weir thereby preventing material located in the joining flat surface forming portion 12 from moving easily into the ordinary portion 11. Therefore, the position in which foaming is generated can be concentrated to the ordinary portion 11.

The moving part 615 is maintained at a higher temperature than the other portions. Thus, material of the ordinary portion 11 can be kept at a higher temperature than the joining flat surface forming portion 12 so that foaming is likely to occur. Thus, the concentration of the foaming generation position can be intensified.

Although material located in the joining flat surface forming portion 12 slightly tries to foam to release a pressure from a portion having no weir toward the ordinary portion 11, the foaming ratio is extremely lower than that of the ordinary portion 11.

By these foamings, such a structure in which the foaming ratio of the ordinary portion 11 sandwiched by the joining flat surface forming portions 12 is higher than the foaming ratio of the joining flat surface forming portion 12 as shown in FIG. 14 is obtained. In the arch portion 10, its entire outer peripheral face is covered with thin film-like skin layer 19 in which foaming is generated little.

Further, generation of sink mark at the time of molding can be suppressed by pressure produced when foaming occurs and obtained appearance characteristic is excellent.

The eject parts 612 having the joining surface forming cavity face 82 for forming the joining flat surface 15 maintain its constant position during molding. Then, the joining flat surface forming portion 12 opposing this is formed in a low foaming condition. Thus, the joining flat surface 15 is finished in a very flat condition in which the flatness of the joining surface forming cavity face 82 is transferred faithfully. Therefore, when this foamed molded product is joined to an automobile body by bonding the double-sided adhesive tape onto these joining flat surfaces 15, sufficient joining performance is obtained.

After the molding is completed, as shown in FIG. 18, the movable part 61 and the fixed part 62 are separated to open the mold and at the same time, the eject parts 612 are advanced from the main body portions 610 to release the foamed molded product 105 from the mold.

After that, to mold a next foamed molded product, as shown in FIG. 19, the eject parts 612 are returned to their original positions and the movable part 61 and the fixed part 62 are matched and tightened together. Then, by moving the moving part 615 to its advance position, it is returned to the state shown in FIG. 15 and by repeating the above-described series of molding, the foamed molded product 105 can be produced continuously.

According to this embodiment, such a foamed molded product 105 in which the foaming ratios of the ordinary portion 11 and the joining flat surface forming portion 12 are controlled can be obtained while suppressing deterioration in appearance. Because in this foamed molded product 105, the joining flat surface forming portion 11 having the joining flat surface 15 has high stiffness and excellent stability in configuration and the flatness of the joining flat surface 15 is improved, the bonding performance can be improved as described above.

By replacing the conventional solid product with the foamed molded product 105 of this embodiment, reduction in weight and reduction in cost due to decreasing material for use can be achieved.

Embodiment 6

This embodiment shows an example in which a mold 706 having a more or less different structure is employed instead of the mold 605 of the first embodiment.

As shown in FIGS. 20-23, the mold 706 for use in this embodiment has a movable part 71 and a fixed part 72 and is provided with a cavity 8 for forming a foamed molded product between these.

As shown in FIG. 20, the movable part 71 includes a main body portion 710 and a pair of eject parts 712, right and left, each having the joining surface forming cavity face 82 for forming each of the two joining flat surfaces 15. Then, a moving part 715 protruded to oppose only the ordinary portion 112 is formed integrally in the center of the main body portion 710. That is, according to this embodiment, by advancing or retracting the entire main body portion 710 including the moving part 715, the moving of the moving part 715 is achieved.

The eject parts 712 are the same as the eject parts 612 of the first embodiment as shown in the same Figure. A projecting portion 825 for forming the groove portion 18 is formed on a boundary between the joining surface forming cavity face 82 for forming the joining flat surface 15 and the moving part 715.

The other structure of the mold 706 is the same as the first embodiment.

When manufacturing the foamed molded product 1 using the mold 706 having the above-described structure and the injection unit 5, as shown in FIG. 20, the movable part 71 and the fixed part 72 are matched and tightened together and by advancing the main body portion 710 including the moving part 715, the volume of the cavity 8 is minimized. The cavity 8 is filled with air as preliminary pressurizing gas through a path (not shown) so as to provide with preliminary pressure. Then, the cavity 8 is filled with synthetic resin material 100 like the fifth embodiment.

After that, with the eject parts 712 left as shown in FIG. 21, the main body portion 710 including the moving part 715 is retracted. Consequently, the volume of the ordinary portion in the cavity 8 is increased largely. In the mold 706 of this embodiment also, as described above, the projecting portion 825 is provided on a boundary portion between the joining surface forming cavity face 82 and the moving part 715. Thus, after the moving part 715 is retracted also, the projecting portion 825 takes a role of so-called weir thereby preventing material located in the joining flat surface forming portion 12 form moving to the ordinary portion 11 easily. Thus, the position in which foaming occurs can be concentrated to the ordinary portion 11.

The moving part 715 is maintained at a temperature higher than the other portions. Thus, like the first embodiment, the material of the ordinary portion 11 can be heated to a temperature higher than the joining flat surface forming portion 12, so that foaming is more likely to occur. Thus, the concentration of the foaming generation position can be intensified.

Next, after molding is completed, as shown in FIG. 22, the movable part 71 and the fixed part 72 are separated to open the mold and by advancing the eject parts 712 from the main body portion 710 largely, the foamed molded product 1 is released.

After that, to mold a next foamed molded product, as shown in FIG. 23, the eject parts 712 are returned to its original position and the movable part 71 and the fixed part 72 are matched and tightened together. Then, after the state of FIG. 20 is regained, the above-described series of the molding are repeated to mold the foamed molded product 105 continuously.

As for the rest, the same operation and effect as the fifth embodiment are obtained.

Embodiment 7

A manufacturing method of the foamed molded product of an embodiment of the present invention is described with reference to FIGS. 24-28.

As shown in FIG. 1, the foamed molded product 1 manufactured according to this embodiment, like the first embodiment, has the joining flat surface 15 to be joined to a joining object and the foaming ratio of the ordinary portion 11 adjacent to the joining flat surface forming portion 12 is higher than the foaming ratio of the joining flat surface forming portion 12 which is a portion gained by projecting the joining flat surface 15 substantially vertically. Further, the foamed molded product 1 of this embodiment has the arch portion 10 whose sectional shape is substantially arcuate and the joining flat surfaces 15 are provided on both ends of the concave side face of the arch portion 10.

As for a specific foaming ratio, when the foaming ratio of the joining flat surface forming portion is assumed to be A and the foaming ratio of the ordinary portion is assumed to be B, B/A is adjusted to fall under a range of 1.01-2.5.

In the arch portion 10, as shown in FIG. 1, thin film-like skin layer 19 in which foaming is generated little is formed on its entire outer peripheral face.

The foamed molded product 1 of this embodiment is a side molding to be joined to an automobile body and configured to be bonded to the automobile body as a joining object using the double-sided adhesive tape on the joining flat surfaces 15.

Next, a manufacturing method of the foamed molded product 1 is described.

For this embodiment, as shown in FIG. 24, a screw 51 is built-in an injection unit 5 and having a foaming agent introducing portion 54 for introducing foaming agent is used.

A mold 607 is connected to the front end of the injection unit 5.

As shown in FIG. 24, the mold 607 of this embodiment has the movable part 61 and the fixed part 62 and there is provided a cavity 8 for forming the foamed molded product 1 between these.

As shown in the same Figure, the movable part 61 includes a main body portion 610, a pair of eject parts 612, right and left, each having a joining surface forming cavity face 82 for forming each of the two joining flat surfaces 15 and a moving part 615 disposed such that it is sandwiched by these.

The moving part 615 is disposed to oppose only the ordinary portion 11 on the concave side face of the arch portion 10 and constructed to be capable of advancing/retracting with respect to the main body portion 610 by an actuator (not shown).

Then, according to this embodiment, the fixed part 62, the moving part 615 and the eject parts 612 form the cavity 8 for forming the foamed molded product 1.

The eject portion 612 is capable of advancing with respect to the main body portion 610 by an actuator (not shown). However, as described later, this functions at the time of releasing a molded product, on the other hand, the eject parts remain integrated with the main body portion 610 at the time of molding.

The fixed part 62 is a mold having a cavity 81 corresponding to the entire face on the convex side of the arch portion 10 and when the mold is opened, the movable part 61 is moved so that it leaves the movable part 61 and when the mold is closed, it approaches the movable part 61.

According to this embodiment, a heater (not shown) is built-in the moving part 615 and is heated to always maintain a temperature over 50° C. On the other hand, the other portions than the moving part 615 are not heated and always maintained at a temperature lower than the moving part 615. Then, a heat insulating material 69 made of phenol resin is attached to the face of the moving part 615, which is a sliding face between the moving part 615 and the eject parts 612.

To manufacture the foamed molded product 1 using the mold 607 having the above-described structure and the injection unit 5, as shown in FIG. 24, the movable part 61 and the fixed part 62 are matched and tightened together and by advancing the moving part 615, the volume of the cavity 8 is minimized. Further, the cavity 8 is filled with air as preliminary pressurizing gas through a path (not shown) to provide with preliminary pressure.

In the injection unit 5, NaHCO₃ as foaming agent is introduced into synthetic resin material and these components are kneaded and advanced along a screw 51. In this embodiment, PP is used as synthetic resin material and Na₂CO₃ (sodium carbonate) generated by thermal decomposition of NaHCO₃ is used as foaming nucleating agent.

When injection is carried out into the cavity 8 from the injection unit 5, appropriate counter pressure is applied to injected synthetic resin material by the preliminary pressurizing gas charged into the cavity 8. Consequently, the synthetic resin material fills the cavity 8 while so-called skin layer 19 (FIG. 1) is formed on the outer surface of the molded product.

After the cavity 8 is filled with the injected synthetic resin material 100 as shown in FIG. 25, the moving part 615 is retracted as shown in FIG. 26. Consequently, the volume of the ordinary portion in the cavity 8 is increased largely.

The mold 607 of this embodiment, as described above, adopts such a heat insulating structure in which the heat insulating material 69 is disposed on a sliding face between the eject parts 612 provided with the joining surface forming cavity face 82 and the moving part 615 and the temperature of the moving part 615 is maintained at a temperature higher than that of other portions.

Thus, material of the ordinary portion 11 is maintained at a temperature higher than that of material of the joining flat surface forming portion 12 so that foaming is likely to occur and the volume is increased. As a result, foaming is generated convergently in this ordinary portion 11.

Although material located in the joining flat surface forming portion 12 tries to generate more or less foaming to release pressure toward the ordinary portion 11, the foaming ratio thereof is extremely lower than the ordinary portion 11.

By these foamings, there is obtained such a structure in which the foaming ratio of the ordinary portion 11 sandwiched by the joining flat surface forming portions 12 is higher than the foaming ratio of the joining flat surface forming portion 12 as shown in FIG. 1. Further in the arch portion 10, its entire outer peripheral face is covered with thin film-like skin layer 19 in which foaming is generated little.

By the pressure produced when such foaming is induced, generation of sink mark at the time of foaming can be suppressed so that an obtained appearance characteristic is excellent.

The eject parts 612 having the joining surface forming cavity face 82 for forming the joining flat surface 15 maintain its constant position during molding. The joining flat surface forming portion 12 opposing this is formed in a low foaming condition. Thus, the joining flat surface 15 is finished into a very flat condition in which the flatness of the joining surface forming cavity face 82 is transferred faithfully. Therefore, when the foamed molded product is joined to an automobile body by bonding double-sided adhesive tape to the joining flat surface 15, its joining performance can be obtained sufficiently.

After molding is completed, as shown in FIG. 27, the movable part 61 and the fixed part 62 are separated to open the mold and by advancing the eject parts 612 from the main body portion 610, the foamed molded product 1 is released.

After that, to mold a next foamed molded product, as shown in FIG. 28, the eject parts 612 are returned to its original position and the movable part 61 and the fixed part 62 are matched and tightened together. Then, after the state of FIG. 24 is regained by advancing the moving part 615 to its advance position, the above-described series of the molding operations are repeated to mold the foamed molded product 1 continuously.

According to this embodiment, such a foamed molded product 1 in which the foaming ratios of the ordinary portion 11 and the joining flat surface forming portion 12 are controlled can be obtained while suppressing deterioration in appearance. Because in this foamed molded product 1, the joining flat surface forming portion 11 having the joining flat surface 15 has high stiffness and excellent stability in configuration and the flatness of the joining flat surface 15 is improved, the bonding performance can be improved as described above.

By replacing the conventional solid product with the foamed molded product 1 of this embodiment, reduction in weight and reduction in cost due to decreasing material for use can be achieved.

Embodiment 8

This embodiment shows an example in which a mold 708 having a more or less different structure is employed instead of the mold 607 of the seventh embodiment.

As shown in FIGS. 29-32, the mold 708 for use in this embodiment has a movable part 71 and a fixed part 72 and is provided with a cavity 8 for forming a foamed molded product between these.

As shown in FIG. 29, the movable part 71 includes a main body portion 710 and a pair of eject parts 712, right and left, each having the joining surface forming cavity face 82 for forming each of the two joining flat surfaces 15. Then, a moving part 715 is formed integrally and protrudedly in the center of the main body portion 710 such that it opposes only the ordinary portion 11. That is, according to this embodiment, by advancing or retracting the entire main body portion 710 including the moving part 715, the moving of the moving part 715 is achieved.

The eject parts 712 are the same as the eject parts 612 of the first embodiment as shown in FIG. 29.

According to this embodiment, a heater (not shown) is built-in the moving part 715 and is heated to always maintain a temperature over 50° C. On the other hand, the other portions than the moving part 715 are not heated and always maintained at a temperature lower than the moving part 715. Then, a heat insulating material 69 made of phenol resin is attached to the face of the moving part 715, which is a sliding face between the moving part 715 and the eject parts 712.

The other structure of the mold 708 is the same as the first embodiment.

To manufacture the foamed molded product 1 using the mold 708 having the above-described structure and the injection unit 5, first, as shown in FIG. 29, the movable part 71 and the fixed part 72 are matched and tightened together and by advancing the main body portion 710 including the moving part 715, the volume of the cavity 8 is minimized. Further, the cavity 8 is charged with air as preliminary pressurizing gas through a path (not shown) to provide with preliminary pressure. Like the first embodiment, the cavity 8 is filled with synthetic resin material 100.

After that, as shown in FIG. 30, with the eject parts 712 left, the main body portion 710 including the moving part 715 is retracted. Consequently, the volume of the ordinary portion in the cavity 8 is increased largely. In the mold 708 of this embodiment also, as described above, such a heat insulating structure in which the heat insulating material 69 is disposed on a sliding face between the eject parts 712 provided with the joining surface forming cavity face 82 and the moving part 715 is adopted and the temperature of the moving part 715 is maintained at a temperature higher than the other portions.

Thus, material of the ordinary portion 11 is kept at a temperature higher than material of the joining flat surface forming portion 12 so that foaming is likely to occur and the volume is increased. Thus, foaming is generated convergently in this ordinary portion 11.

Although material located in the joining flat surface forming portion 12 tries to cause more or less foaming to release pressure toward the ordinary portion 11, the foaming ratio is extremely lower than that of the ordinary portion 11.

After molding is completed, as shown in FIG. 31, the movable part 71 and the fixed part 72 are separated to open the mold and by advancing the eject parts 712 from the main body portion 710 largely, the foamed molded product 1 is released.

After that, to mold a next foamed molded product, as shown in FIG. 32, the eject parts 712 are returned to its original position and the movable part 71 and the fixed part 72 are matched and tightened together. Then, after the state of FIG. 29 is regained, the above-described series of the molding operations are repeated to mold the foamed molded product 1 continuously.

As for the rest, the same operation and effect as the seventh embodiment are obtained.

Further, by using the same method as the seventh and eighth embodiments, the foamed molded products 2, 3 of the third, fourth embodiment can be manufactured.

Embodiment 9

The foamed molded product and manufacturing method of this embodiment is described with reference to FIGS. 33-38.

The foamed molded product 109 of this embodiment, as shown in FIG. 33, has the arch portion 10 whose sectional shape is substantially arcuate and the joining flat surfaces 15 to be joined to a joining object are provided on both ends of the concave side face of the arch portion 10.

The foaming ratio of the ordinary portion sandwiched by the joining flat surface forming portions 12 is substantially equal to the foaming ratio of the joining flat surface forming portion 12 which is erected from the joining flat surface 15 on each of the both ends of the arch portion 10.

As for specific foaming ratio, when the foaming ratio of the joining flat surface forming portion is assumed to be A and the foaming ratio of the ordinary portion is assumed to be B, B/A is adjusted to fall under a range of 0.90-1.10.

In the arch portion 10, as shown in FIG. 33, thin film-like skin layer 19 in which foaming occurs little, is formed on the entire outer peripheral face.

The foamed molded product 1 of this embodiment is a side molding to be joined to an automobile body and configured to be bonded to the automobile body as a joining object using the double-sided adhesive tape on the joining flat surfaces 15.

Next, a manufacturing method of the foamed molded product 1 is described.

In this embodiment, as shown in FIG. 34, a screw 51 is built-in an injection unit 5 and having a foaming agent introducing portion 54 for introducing foaming agent is used.

A mold 609 is connected to the front end of the injection unit 5.

As shown in FIG. 34, the mold 609 of this embodiment has the movable part 61 and the fixed part 62 and there is provided a cavity 8 for forming the foamed molded product 109 between these.

As shown in the same Figure, the movable part 61 includes a main body portion 610, a pair of the eject parts 612, right and left, each having the joining surface forming cavity faces 82 for forming each of the two joining flat surfaces 15 and the moving part 615 disposed such that it is sandwiched by these.

The moving part 615 is disposed to oppose only the ordinary portion 11 in the concave side face of the arch portion 10 and constructed to be capable of advancing/retracting with respect to the main body portion 610 by an actuator (not shown).

The movable part 61 and the fixed part 62 are employed in a fixed condition at the time of molding and included in the concept of the fixed part of the second aspect of the present invention.

The eject parts 612 are capable of advancing/retracting with respect to the main body portion 610 by an actuator (not shown). However, as described later, this functions at the time of releasing a completed product from the mold, on the other hand, the eject parts remain integrated with the main body portion 610 at the time of molding.

The fixed part 62 is a mold having a cavity face 81 corresponding to the entire convex side of the arch portion 10 and when the mold is opened, it leaves the movable part 61 relatively and when the mold is closed, it approaches the movable part 61 relatively.

According to this embodiment, a heater (not shown) is built-in the eject parts 612 and the joining surface forming cavity face 82 is heated to always maintain a temperature over 50° C. On the other hand, the moving part 615 is not heated and always maintained at a temperature lower than the joining surface forming cavity face 82. Then, a heat insulating material 69 made of phenol resin is attached to the face of the moving part 615, which is a sliding face between the moving part 615 and the eject parts 612.

To manufacture the foamed molded product 1 using the mold 609 having the above-described structure and the injection unit 5, first, as shown in FIG. 34, the movable part 61 and the fixed part 62 are matched and tightened together and by advancing the moving part 615, the volume of the cavity 8 is minimized. Further, the cavity 8 is filled with air as preliminary pressurizing gas through a path (not shown) so as to provide with preliminary pressure.

In the injection unit 5, NaHCO₃ as foaming agent is introduced into synthetic resin material and these components are kneaded and advanced along a screw 51. In this embodiment, PP is used as synthetic resin material and Na₂CO₃ (sodium carbonate) generated by thermal decomposition of NaHCO₃ is used as foaming nucleating agent.

When injection is carried out into the cavity 8 from the injection unit 5, appropriate counter pressure is applied to injected synthetic resin material by the preliminary pressurizing gas charged into the cavity 8. Consequently, the synthetic resin material fills the cavity 8 while so-called skin layer 19 (FIG. 33) is formed on the outer surface of the molded product.

After the cavity 8 is filled with the injected synthetic resin material 100 as shown in FIG. 35, the moving part 615 is retracted as shown in FIG. 36. Consequently, the volume of the ordinary portion 11 in the cavity 8 is increased largely so that foaming begins at this portion.

As described above, the mold 609 of this embodiment adopts such a structure in which the heat insulating material 69 is disposed on a sliding face between the eject parts 612 provided with the joining surface forming cavity face 82 and the moving part 615 and the temperature of the joining surface forming cavity face 82 is kept higher than the temperature of the other moving part 615 and the like.

Easiness of foaming in the material itself in contact with the mold is higher in material of the joining flat surface forming portion 12 under a high temperature than material of the ordinary portion 11. Thus, foaming in the joining surface forming portion 12 is urged at the same time accompanied by flow of material.

Consequently, entirely substantially uniform foaming condition is obtained due to easiness in foaming by increased volume and easiness in foaming under high temperatures.

By these foamings, as shown in FIG. 33, such a structure in which the foaming ratio of the joining flat surface forming portion 12 and the foaming ratio in the ordinary portion 11 sandwiched by the joining flat surface forming portions 12 are substantially equal is obtained. Further, the arch portion 10 is constructed that its entire outer peripheral face is covered with thin film-like skin layer 19 in which foaming is generated little.

By pressure produced when such foaming is induced, generation of sink mark at the time of molding can be suppressed so that obtained appearance characteristic is excellent.

The eject parts 612 having the joining surface forming cavity face 82 for forming the joining flat surface 15 are kept at its constant position during molding. Thus, the joining flat surface 15 is finished in a very flat condition in which the flatness of the joining surface forming cavity face 82 is transferred faithfully. Thus, when the foamed molded product is joined to an automobile body by bonding double-sided adhesive tape to this joining flat surface 15, its joining performance can be secured sufficiently.

After molding is completed, as shown in FIG. 37, the movable part 61 and the fixed part 62 are separated to open the mold and at the same time, by advancing the eject parts 612 from the main body portion 610, the completed foamed molded product 1 is released from the mold.

After that, as shown in FIG. 38, to mold a next foamed molded product, the eject parts 612 are returned to its original position and the movable part 61 and the fixed part 62 are matched and tightened together. Then, after the state of FIG. 34 is regained by moving the moving part 615 to its advance position, the above-described series of molding operations are repeated to mold the foamed molded product 109 continuously.

According to this embodiment, it is possible to obtain such a foamed molded product 109 in which the foaming ratios of the ordinary portion 11 and the joining flat surface forming portion 12 are controlled to be substantially equal while suppressing deterioration in appearance. Because the flatness of the joining flat surface 15 is improved in this foamed molded product 109, the bonding performance can be improved.

Further, by replacing the conventional solid product with the foamed molded product 109 of this embodiment, reduction in weight and reduction in cost due to decreasing material for use can be achieved.

Embodiment 10

This embodiment shows an example in which a mold 709 having a more or less different structure is employed instead of the mold 609 of the ninth embodiment.

The mold 709 for use in this embodiment, as shown in FIGS. 39-42, includes a movable part 71 and a fixed part 72 and there is provided a cavity 8 for forming the arch portion 10 between these.

As shown in the same Figure, the movable part 71 includes a main body portion 710 and a pair of eject parts 712, right and left, each having the joining surface forming cavity face 82 for forming each of the two joining flat surfaces 15. Then, a moving part 715 is formed integrally and protrudedly in the center of the main body portion 710 such that it opposes only the ordinary portion 11. That is, according to this embodiment, by advancing or retracting the entire main body portion 710 including the moving part 715, the moving of the moving part 715 is achieved.

A heater (not shown) is built-in the eject parts 712 and the joining surface forming cavity face 82 is heated so that the temperature thereof is always kept over 50° C. On the other hand, the moving part 715 is not heated especially but always kept at a temperature lower than the joining surface forming cavity face 82. Then, a heat insulating material 69 made of phenol resin is attached to the face of the moving part 715, which is a sliding face between the moving part 715 and the eject parts 712.

The other structure of the mold 709 is the same as the first embodiment.

To manufacture the foamed molded product 1 using the mold 709 having the above-described structure and the injection unit 5, as shown in FIG. 39, the movable part 71 and the fixed part 72 are matched and tightened together and by advancing the main body portion 710 including the moving part 715, the volume of the cavity 8 is minimized. Further, the cavity 8 is filled with air as preliminary pressurizing gas through a path (not shown) to provide with preliminary pressure. Like the first embodiment, the cavity 8 is filled with synthetic resin material 100.

After that, as shown in FIG. 40, with the eject parts 712 left, the main body portion 710 including the moving part 715 is retracted. Consequently, the volume of the ordinary portion 11 in the cavity 8 is increased largely and foaming begins at this portion. The mold 709 of this embodiment also, as described above, adopts such a heat insulating structure in which the heat insulating material 69 is disposed on a sliding face between the eject parts 712 provided with the joining surface forming cavity face 82 and the moving part 715 and the temperature of the joining surface forming cavity face 82 is kept at a higher temperature than the temperature of the other moving part 715 and the like.

For the reason, easiness of foaming of material itself in contact with the mold is higher in material of the joining flat surface forming portion 12 kept at high temperatures than material of the ordinary portion 11. Thus, foaming of the joining flat surface forming portion 12 is urged at the same time accompanied by flow of material.

Consequently, entirely substantially equal foaming condition is obtained due to easiness of foaming by increased volume and easiness of foaming under high temperatures.

After molding is completed, as shown in FIG. 41, the movable part 71 and the fixed part 72 are separated to open the mold and by advancing the eject parts 712 from the main body portion 710 largely, the foamed molded product 1 is released from the mold.

After that, as shown in FIG. 42, to produce a next foamed molded product, the eject parts 712 are returned to its original position and the movable part 71 and the fixed part 72 are matched and tightened together. After the state of FIG. 39 is regained, the above-described series of molding operations are repeated to mold the foamed molded product 109 continuously.

The same operation and effect as the ninth embodiment are obtained.

Embodiment 11

This embodiment shows a modification produced by changing the shape of the foamed molded product of the ninth embodiment.

As shown in FIG. 43, the foamed molded product 202 of this embodiment has the arch portion 20 and the ornament portion 28 adjoining an end thereof.

The arch portion 20 of this foamed molded product 202 has joining flat surfaces 25 to be joined to a joining object on both ends of the concave side face of the arch portion 20. Then, the foaming ratio of the joining flat surface forming portion 22, which is erected from the joining flat surface 25 on each of both ends of the arch portion 20 is substantially equal to the foaming ratio of the ordinary portion 21 sandwiched by joining flat surface forming portions 22.

To manufacture the foamed molded product 202, a mold (not shown) having a cavity for forming the arch portion 20 and an ornament cavity for forming an ornament portion 28 is used and the same operation as the ninth embodiment is carried out for that cavity portion. Consequently, the foaming ratios of the ordinary portion and the joining flat surface forming portion can be controlled in the same way as the ninth embodiment and the other matters are the same as the ninth embodiment.

Embodiment 12

This embodiment also shows a modification produced by changing the shape of the foamed molded product of the ninth embodiment.

As shown in FIG. 44, the foamed molded product 302 of this embodiment includes a first arch portion 310, a second arch portion 320 and an ornament portion 38 adjoining between these.

The first arch portion 310 of this foamed molded product 3 has joining flat surfaces 351, 352 to be bonded to a joining object on both ends of a concave side face of the first arch portion 310. The foaming ratio of the joining flat surface forming portion 312 erected from the joining flat surfaces 351, 352 on both ends of the first arch portion 310 is substantially equal to the foaming ratio of the ordinary portion 311 sandwiched by the joining flat surface forming portion 312.

Likewise, the second arch portion 320 has joining flat surfaces 353, 354 to be bonded to a joining object on both ends of the concave side face of the second arch portion 320. Then, the foaming ratio of the joining flat surface forming portion 322 erected from the joining flat surfaces 353, 354 on both ends of the second arch portion 320 is substantially equal to the foaming ratio of the ordinary portion 321 sandwiched by the joining flat surface forming portion 322.

To manufacture a foamed molded product 302, a mold (not shown) having two cavities for forming the first arch portion 310 and the second arch portion 320 and an ornament cavity for forming an ornament portion 38 is employed and the same operation as the ninth embodiment is carried out for those two cavity portions. Consequently, like the ninth embodiment, the foaming ratios of the ordinary portion and the joining flat surface forming portions can be controlled. The other matters are the same as the ninth embodiment.

Obviously, numerous modifications and variations of the present invention are possible in light of the above teachings. It is therefore to be understood that, within the scope of the appended claims, the invention may be practiced otherwise than as specifically described here. 

1. A foamed molded product having a joining flat surface to be joined to a joining object, the formed molded product comprising: a joining flat surface forming portion provided with the joining flat surface; and an ordinary portion which is other portion than the joining flat surface forming portion; and wherein the foaming ratio of the joining flat surface forming portion provided with the joining flat surface is higher than the foaming ratio of an ordinary portion.
 2. The foamed molded product according to claim 1, wherein the joining flat surface forming portions are provided on an end or both ends of the ordinary portion.
 3. The foamed molded product according to claim 1, comprising an arch portion as the ordinary portion whose sectional shape is substantially arcuate, and the joining flat surfaces provided on both ends of a concave side face of the arch portion.
 4. The foamed molded product according to claim 1, wherein when the foaming ratio of the joining flat surface forming portion is assumed to be A and the foaming ratio of the ordinary portion is assumed to be B, B/A=1.01-2.5.
 5. The foamed molded product according to claim 1, further comprising a groove portion which is dented from the same side face as a face provided with the joining flat surface, the groove formed between the joining flat surface forming portion and the ordinary portion.
 6. The foamed molded product according to claim 1, wherein the foamed molded product is a side molding to be joined to an automobile body.
 7. A manufacturing method of foamed molded product having a joining flat surface to be joined to a joining object in which the foaming ratio of an ordinary portion is higher than the foaming ratio of a joining flat surface forming portion provided with the joining flat surface, the manufacturing method comprising: using a mold comprising at least a fixed part and a moving part advancing/retracting with respect to the fixed part and containing a cavity for forming the foamed molded product, the moving part being disposed adjacent to a joining surface forming cavity face for forming the joining flat surface in the cavity such that the moving part opposes the ordinary portion; injecting synthetic resin material containing foaming agent or synthetic resin material containing foaming gas into the cavity; and retracting the moving part to increase the volume of the ordinary portion in order to urge the foaming.
 8. The manufacturing method of foamed molded product according to claim 7, wherein the mold comprises a movable part provided with the moving part capable of advancing/retracting relatively so that the movable part and the fixed part are capable of advancing/retracting relative to each other.
 9. The manufacturing method of foamed molded product according to claim 7, wherein the mold comprises an eject part for releasing the foamed molded product after molding and the joining surface forming cavity face is provided at the front end face of the eject part.
 10. The manufacturing method of foamed molded product according to claim 7, wherein the foamed molded product has an arch portion whose sectional shape is substantially arcuate, the joining flat surfaces are provided on both ends of a concave side face of the arch portion and the moving part is disposed such that it is sandwiched by two joining surface forming cavity faces.
 11. The manufacturing method of foamed molded product according to claim 7, further comprising filling the cavity with preliminary pressurizing gas to provide with preliminary pressure prior to the injecting.
 12. The manufacturing method of foamed molded product according to claim 7, wherein the foamed molded product in which groove portions dented from the same face as a face provided with the joining flat surfaces are formed between the joining flat surface forming portion and the ordinary portion, and wherein the mold comprises a projecting portion for forming the groove portion formed on a boundary between the joining surface forming cavity face and the moving part.
 13. The manufacturing method of foamed molded product according to claim 7, wherein the moving part is kept at a temperature higher than at least the joining surface forming cavity face.
 14. The manufacturing method of foamed molded product according to claim 7, wherein between the moving part and a mold part adjacent thereto, a heat insulating structure for reducing heat transmission between the both is provided and with the moving part kept at a temperature higher than other portions, synthetic resin material containing foaming agent or synthetic resin material containing foaming gas is injected into the cavity and after that, by retracting the moving part, the volume of the ordinary portion is increased in volume to urge the foaming.
 15. A foamed molded product having a joining flat surface to be joined to a joining object, the formed molded product comprising: a joining flat surface forming portion provided with the joining flat surface; and an ordinary portion which is other portion than the joining flat surface forming portion; and wherein the foaming ratio of the joining flat surface forming portion provided with the joining flat surface and the foaming ratio of the ordinary portion are substantially equal.
 16. The foamed molded product according to claim 15, wherein the joining flat surface forming portions are provided on an end or both ends of the ordinary portion.
 17. The foamed molded product according to claim 15, comprising an arch portion as the ordinary portion whose sectional shape is substantially arcuate, and the joining flat surfaces provided on both ends of the concave side face of the arch portion.
 18. The foamed molded product according to claim 15, wherein when the foaming ratio of the joining flat surface forming portion is assumed to be A and the foaming ratio of the ordinary portion is assumed to be B, B/A=0.90-1.10.
 19. The foamed molded product according to claim 15, wherein the foamed molded product is a side molding to be joined to an automobile body.
 20. A manufacturing method of foamed molded product having a joining flat surface to be joined to a joining object in which the foaming ratio of a joining flat surface forming portion provided with the joining flat surface and the foaming ratio of an ordinary portion are substantially equal, the manufacturing method comprising: using a mold having a fixed part and a moving part advancing/retracting with respect to the fixed part and containing a cavity for forming the foamed molded product, the moving part being disposed such that it is sandwiched by the joining surface forming cavity faces for forming the joining flat surfaces in the cavity, the moving part opposing the ordinary portion, wherein between the moving part and a mold portion adjacent thereto, a heat insulating structure for reducing heat transmission between the both is provided, keeping the joining surface forming cavity face at a temperature higher than that of the moving part while keeping the moving part at a temperature lower than that of the joining surface forming cavity face; injecting synthetic resin material containing foaming agent or synthetic resin material containing foaming gas into the cavity, retracting the moving part to increase the volume of the ordinary portion in order to urge the foaming.
 21. The manufacturing method of foamed molded product according to claim 20, wherein the mold comprises a movable part provided with the moving part capable of advancing/retracting relatively so that the movable part and the fixed part are capable of advancing/retracting relative to each other.
 22. The manufacturing method of foamed molded product according to claim 20, wherein the mold comprises an eject part for releasing a foamed molded product after molding and the joining surface forming cavity face is provided at the front end face of the eject part.
 23. The manufacturing method of foamed molded product according to claim 20, further comprising filling the cavity with preliminary pressurizing gas to provide with preliminary pressure prior to the injecting. 